Damper for contact breaker devices for electromagnetic vibrating members



Nov. 25, 1924. 1,517,217

A. H. MATrRE ET AL DAMPER FOR CONTACT BREAKER DEVICES FOR ELECTROMAGNETIC VIBRATING MEIBERS Nov. 25, 1924. A 1,517,217

A. H. MAITRE ET AL DAMPER FOR CONTACT BREAKER DEVICES FOR ELECTROMAGNETIC VIBRATING MEMBERS F11 April 14, 1922 2 fl ng- 1, 2

V/c 7'08 Him/91 64s ro/v MART/N 6 i601! flmmeys Patented Nov. 25, 1924.

UNITED STATES PATENT OFFICE.

ALGIDE HECTOR MA'i'rRE AND VICTOR HENRI GASTON MARTIN. OF ROUEN. FRANCE.

DAMPER FUR CONTACT-BREAKER DEVICES FOR ELECTROMAGNETIC VIBRATING MEMBERS.

Application filed April 14, 1922, Serial No. 552,503.

To uZ/wmhom it may concern:

Be it known that we, Atoms Hno'ron Mairm. and Yuvron H nvm GASTON -MART1N- both citizens of the French Re ublic, and both residents of 92 Rue de lalipublique, lloiicn. Departmnet of Seine In-frieure, France, have invented new and useful Improvements in Dampers for Contact- Breaker Devices for Electromagnetic Vibrating Members, of which the following is a specification.

The present invention has for an object to damp rapidly all oscillatory motion of a movable member; it relates more especially to contact-breaker devices for electro-ma-gnetic vibrating members, and in particular to the arrangements described in the United States Patents No. 1,106,280 of August 4, 1914 and No. 1,188,295 of June 20, 1916.

These last arrangements are characterized particularly by the fact that the contact member, intended to close the electric circuit by its contact with the vibrating body (gong, plate, string or other element), is carried by a movable arm mounted upon a pivot and adapted to perform oscillations of small amplitude.

Experience has shown that in order to oblain a pure note, and to allow this note to be established rapidly, it is of advantage, especially in the case of vibrating pianostrings, to reduce as far as possible the am plitude of the oscillations of the movable i'olilzul'. member.

The present invention relates to a device allowing this result to be attained and is based upon the principle of braking or damping the oscillations of the movable contact member by means arranged in such a way as to produce no oscillatory reaction in the direction of the displacement oi the w l movable ontact member.

The annexed drawings represent. by way of example various forms of construction in accordance with the invention:

Fig. 1 is an elevation of one form of the invention applied to a device for vibrating a piano string;

Fig. 2 is a horizontal section upon line 2-2 of Fig. 1;

Fig. 3 is a vertical section upon line 3-3 of Fig. 1;

Fig. 4 is a perspective view of a meohe nisni for renewing the points of contact in the construct-ion shown in Figs. 1 to 3;

electromagnet which vibrates it, and c a rocking arm carrying the movable contact piece 0. The movable arm 0 is mounted upon the pivot 0 supported by a wooden block I integral with another wooden block m, the pivot c terminating in two cone (-enters upon which are journaled the two legs of the stirrup-shaped oscillating plate c. There is a. lead weight a offset in relation to the pivotal axis 0 of the plate and serving to balance the oscillating plate 0 as well as to provide means for riveting together the two legs of the stirrup-shaped oscillating plate. A steel :plate 0" in the shape of a cylinder divided along a generatrix, is arranged to form a spring, its free ends being engaged slidably in a groove formed at the lower end of the oscillating plate 0; the movable contact piece 0 consists of a blllldlt of annealed silver wires, clamped in the c lindrical plate spring 0* and therefore, ad

justable in position in the groove at. the lower end of the oscillating plate 1-. 'llnstirrup-forming legs of this oscillating platic pivot freely with slight play upon the coin ieal points of the spindle c". To the mow able arm 0 there is suspended, by a metal wire j clamped beneath-a screw j", a piston j plunged in a more or less viscous liquid contained in a vessel 71:, supported by the block m. the level of the liquid Z with an orilicc l|;|\ iug a tubular neck Z to pri-vi-nt the liquid from overflowing, either as u n-sult o l' PXPZHJ sion or because of the apparatus being tilt ed. This liquid can be rendered immune from oxidation by covering it with another liquid of ii hter density not subject to oXi' dation, sue as watchmakers oil.

The vessel It supports by means of the plat 10 an electromagnet I) connected in series. in the energizing circuit of the main cletromagnet b, exerting its attractional force upon the pianoovire or string a. The stationary contact a is mounted upon a metal wire a" hooked at one end to the stringfl, and at the This vessel la is provided above -;i.

llll

other end to the member a. As a vresult of the method of mounting the' electromagnet I), the attraction of the armature e carried by the movable arm 0, by the electromagnet b, that is to say the break of contact at c, a, takes place in synchronism with the variations of the energizing current of the main electromagnet b.

The two wooden blocks l and m are to gether pivoted at n upon a third wooden block 0, firmly secured by a bolt q to a metal angle-bracket 72, itself rigidly fixed to the body of the instrument.

The working of the device is as follows:

' 'lhe oscillating plate 0 is balanced by the cocentric weight 0 in such a way that in the absence of current passing in the energizing circuit of the electromagnets b b, the movable contact piece 0 presses lightly upon the contact a. When the plate 0 oscillates under the influence of the electromagnet b and the weights acting upon the movable arm, the piston j moves in the body of viscous li uid It, so that any motion of the oscillating-p ate 0 is simply braked or slowed down without being prevented and without being followed by an opposite reactionalmovement, the displacements of the piston" compelling the liquid: to circulate through the restricted spaces which separate-the piston from the walls of the 'containin vesseln nder these conditions a considerab e-resistance is offered by the liquid to rapid-movement of the piston and thereforeof the oscillating plate '0.

The position of the armature e in relation to the electromagnet b can'be adjusted by means of a square-headed screw 41, engaged in the wooden block m and abutting against the part 0- under-the :action' of -an'ropposing spring a; the armature e' canthus be maintained constantly at the same distance from the electromagnet-b even if a slight wear of the contacts a a should be produced after several years of'op'eration. V

In order to effect the replacement of the metal wires acarr ing the contact ieces a, the vessel is israis so that the woo en block I pivots around its axis-11, compressing the spring 15" between the blocks in and 0; the plate a under the contact thereupon releases the contact piece in allowing'rea'dyi access to the latter. It has been found'advantageous to constantly renew the points of contact between the surfaces 0 a and to cause continual 111bbing of these parts against one another. For this purpose the metal angle-bracket shown in Figure 1 supporting the device is itself supported as shown in Figure 4 by eccentric rods p, the driving eccentrics p of which are secured upon a horizontal shaft 71 This shaft revoluble in bearings 7) carries at one end a pulley p driven by the shade controlling means, i. e. by means of the hi1 belt 7) by the mechanism (not shown) for producing the gradations of forte, piano and planlSSlIIlO.

This mechanism therefore produces by the rotation imparted to the shaft p an upward and downward movement of the anglesection bar p, and causes rubbing of each of the contact pieces 0 upon the corresponding contact a. The angle-bar 72 carries slides g) each having a slot in which there works a screw p fixed to a vertical guiding surface so as to ensure a truly vertical motion of the bar 72.

Figures 5 and 6 represent the application of the damping device with piston submerged in a viscous liquid, to the case of the \ilil'zv tion of a gong (1 operated by the elcclro-mag not b; the plate 0 integral with the pivot c" and carrying the movable contact 0 comprises an arm a directed at right angles in relation to the plate 0 and connected by a metal wirc j to a small piston j submerged in a viscous' liquid, for example castor oil, in the tubular vessel k. The latter is supported by means of clips or collars 0! directly upon a bracket d integral with the support (l in which the contact device is pivoted.

When the plate 0 oscillates under the influence of the electromagnet 12, its oscillations are rapidly damped by the resistance opposed by the viscous liquid to the displacements of the plunger 7'.

The tube It being of very small diameter there is no need to provide, as in the example illustrated in Figures 1 to 3, a constricted neck to prevent the liquid from overflowing; the liquid is maintained in the tube by capillarity in spite of possible tilting or expansion- It will' be understood that the forms of construction described and shown in the drawings have'been given merely by way off-examples, and that they may receive a large number of detail modifications without departing from the scope of the claims, for example as regards the shape of the movable contact piece and its method of excitation; the electromagnets I) may be connected in parallel or in series with the main electromagnet b and they may tend In break the contact at a, when these parts are in contactJ-Or on the contrary they may tend to bring the contacts together when they are separated by an opposing spring, weight or other force.

\Vhat we claim is:

1. In an electric circuit, an electro-magnetically vibrated member, a contact vibrating in unison therewith, a second contact cooperating with the first mentioned contact to complete the operating electromagnetic circuit, a movable arm carrying said second contact, electrical means operating in said circuit and adapted to vibrate the said sec ond contact and to produce forced breaks at the beginning of the vibration. a fixed St l lln

vessel containing a viscous liquid, a plunger connected to the movable arm and immersed in said viscous liquid, said plunger being of sectional area slightly less than that of the liquid-containing vessel, for the purpose described.

2. In a music instrument, an electric circuit, an electro-magnetically vibrated string, a contact vibrating in unison therewith, a second contact cooperating with the first mentioned contact to complete the operating clcctro-magnetic circuit, a movable arm carrying said second contact, electrical means operating in said circuit and adapted to vibrate the second contact and to produce forced breaks at the beginning of the vibration of the string, a fixed vessel containing a viscous liquid, a plunger connected to the movable arm and immersed in said viscous liquid, said plunger being of sectional area slightly less than that of the liquid-containing vessel, for the purpose described.

:3. In an electric circuit, an electro-magnetically vibrated member, a contact vibrating in unison therewith, a second contact cooperating With the first mentioned contact to complete the operating electro-magnetic circuit, a frame member, a rocker arm pivotally mounted on said frame member and carrying said second contact, means electromagnetically operating in said circuit and adapted to vibrate said second contact and to produce forced breaks at the beginning of the vibration, said means comprising an electromagnet carried by theframe member and an armature carried by the rocker arm, a fixed vessel containing a viscous liquid, plunger connected to the movable arm and immersed in said viscous liquid, said plunger being of sectional area slightly less than that of the liquid-containing vessel, for the purpose described.

4. In an arrangement as claimed in claim 3, the provision of means for adjusting the armature, carried by the rocking arm, in relation to the electromagnet vibrating the movable contact.

5. In an arrangement as claimed in claim 3, the provision of means for ensuring a continuous relative displacement of both contacts and a continuous friction of said contacts the one against the other, for the purpose described.

6. In an arrangement as claimed in claim 3, the provision of a bar carrying the frame member, supporting the electromagnetically vibrated second contact, and of means for reciprocating said bar, for the purpose described.

7. In an arrangement as claimed in claim 3, applied to a piano, a bar carrying the frame members of all of the electro-magnetically vibrated movable second contacts, shade controlling means for the piano, and means actuated by said shade controlling means adapted to reciprocate said bar and ensure a continuous relative displacement of both contacts of each pair and a continuous friction of one contact against the other of the said pair, for the purpose described.

In testimony whereof they have signed their names to this specification.

ALClDE HECTOR MAlTRI-l.

VICTOR HENRI GASTON MARTIN. \Vitnesses:

HOWARD E. TAGGART, MAURICE LANJoU. 

